It is commonplace in the electronic arts, especially semiconductor arts, to etch trenches of various depths into substrates on which various electronic devices and/or integrated circuits (ICs) and/or micro-electro-mechanical system (“MEMS”) elements are being fabricated. Of particular interest are trenches whose dimensions (e.g., width and depth) are of the order of a few micrometers and where at least one of the dimensions of the trench opening is significantly smaller than the others. In this realm special etching problems can be encountered.